With the increasing demand for microsatellites, research on low-power electric thrusters suitable for satellites has been actively conducted.In this study, a conceptual design of an RF ion thruster for microsatellites was performed.The mission orbit for a 6U CubeSat was defined, and the propulsion system requirements were analyzed to utilize argon as the propellant and to operate with 20 W of RF power, ensuring a thrust of approximately 0.3 mN and a specific impulse of 1500 s.A detailed conceptual design of the RF ion thruster, including the grid system and plasma generation chamber, was conducted under the given constraints.Consequently, the thruster was designed to generate a thrust of 0.3 mN and a specific impulse of 1530 s at an argon flow rate of 0.35 sccm.